1. Field of the Invention
The present invention relates generally to a wireless communications network, and more particularly, to a method of adjusting a power level of communications over a channel in a wireless communications network.
2. Description of the Related Art
Wireless communication systems typically include radio network controllers (RNCs) or mobile switching centers (MSCs), each managing a plurality of base stations where one or more base stations serve a geographic area commonly referred to as a cell. Users or subscribers of the wireless communication system use a mobile station (e.g., a cell phone, a PDA, a laptop, etc.) to communicate with each other and/or with another communication system (e.g., the Internet).
Wireless communication systems operate in accordance with established rules promulgated by governmental and industry groups. These rules are established as standards with which wireless communication systems comply. The standards contain various protocols that determine an acceptable operation for the wireless communication systems. A protocol is a set of rules with which a communication system is to be initiated, maintained and terminated. Equipment at the base stations and controllers (e.g., RNC, MSC, etc.) are referred to as system or network equipment. In wireless communication systems, communication may occur between two mobile stations or between a mobile station and system equipment.
Communication between mobile stations and one or more base stations is performed over a number of communication channels. The communication channels may be classified as either uplink (e.g., transmitted from the mobile station to the one or more base stations) or downlink (e.g., transmitted from the one or more base stations to the mobile station) communication channels. The communication channels may further be classified as being either shared or dedicated channels.
A dedicated channel is a communication link used to transfer data between a designated mobile station and a designated base station. In contrast, a shared control channel may form a communication link between any base station and any mobile station. A base station (e.g., for downlink communications) or mobile station (e.g., for uplink communications) may periodically, upon request, assume control of a shared channel, with only one entity controlling the shared channel at a given time. For example, a first mobile station requesting an uplink shared channel may transmit on the uplink shared channel for a given period of time (e.g., measured by a sub-frames). When the first mobile station is no longer assigned to the uplink shared channel (e.g., because the uplink shared channel is reassigned, because the first mobile station completes transmitting, etc.), the uplink shared channel may be reassigned to another mobile station.
Establishing power levels for transmissions on communication channels (e.g., uplink channels, downlink channels, dedicated channels, shared channels, etc.) between mobile stations and base stations is a major factor in the performance of mobile communication systems because higher transmission power levels are typically associated with higher system interference as well as increased power consumption. Further, whether or not a mobile station is engaged in soft handoff may complicate a process of selecting effective transmission power levels.